Motor driven model airplane

ABSTRACT

This disclosure relates to a motor-driven model airplane that can be put together from a few prefabricated individual parts and which has particular features for preventing damage to the vital parts thereof during impact. The fuselage, wings and tail unit of the plane are formed of plastic half shells which are lined with a foam plastic material. Impact loads applied to the vital parts of the plane as a result of crashes thereof are transmitted to the foam plastic material and evenly distributed therethrough thereby reducing the possibility of an impact failure at a particular point in the airplane.

0 United States Patent 13590517 [72] Inventors Ulric]! llegehr 2,920,682 [H960 Lindberg 46/76 Laurensberg; 3,041,220 6/1962 Martin et alv 220/9 F Roland mfl Aachen. Germany 3,388,651 6/1968 Axelrod 46/76 1 pp 795-441 OTHER REFERENCES [221 Flled 1969 Pekspan Expandable Polystrene Catalogue" 171-90 of [45] Patented July6, 1971 Do Ch [C F b 958 m1 Assignee Simprop'Electronic w e'mca C Hnrsewinkel, Germany Primary Examiner-Robert Peshock [32} Priority Aug. I0. 1968 Attorney-Diner, Brown, Ramik & Holt [33] Germany [3!] P17280011 [54] DmvEN MODEL AIRPLANE ABSTRACT: This disclosure relates to a motor-driven model s, 19 Drawing Figs.

airplane that can be put together from a few prefabricated m- 46/76 dividual parts and which has particular features for preventing l Cl A631 27/00 damage to the vital parts thereof during impact. The fuselage, (50] Field of Search 46/74, 75, wings and u unit f the plane are f r ed f p|astic h lf h ll 76; 220/9 F which are lined with a foam plastic material. Impact loads aplied to the vital arts of the lane as a result of crashes [56] Reterenms Cited thereof are transmit ted to the foafn plastic material and evenly UNITED STATES PATENTS distributed therethrough thereby reducing the possibility of an 2,055,620 9/1936 Boehme 46/76 impact failure at a particular point in the airplane.

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lnremars uuzlcu REGEHR ROLAND DIETEL W QZ ATTORNEYS MUTUR DRIVEN MODEL AllllillPLlhNE This invention relates to a motor-driven model airplane, and more particularly to a model airplane having particular features for preventing damage to the vital parts thereof as a result of impact loads incurred during crashes.

Still more particularly, the invention is directed to a model airplane capable of withstanding high stress loads incurred during stunt flying, and which can be put together by the do it-yourselfer" in a short time from a few prefabricated in dividual parts and can be made ready to fly. The model plane is both sturdy and extremely economical.

Prior attempts have been made to produce motor driven model airplanes that are at once economical and that can withstand relatively high stresses and impact loads incurred during the frequent crashes of motor-driven model airplanes. In these prior attempts the planes were produced from deep drawn plastic, but this resulted in difficulties concerning strength, distribution of weight in the plane, of the mounting support of the motor, of the wings, of the body, the landing gear and the nose wheel. Moreover, the problem of easily broken wings remained as acute as ever.

Therefore, in recognition of these problems and while avoiding the difficulties of known designs, it is an object of this invention to provide a motor-driven model airplane that is capable of withstanding impact loads upon crashes thereof without damage to the vital parts of the plane.

More particularly, it is an object of this invention to provide a model airplane having a fuselage, wings and horizontal tail unit formed of plastic half shells, and wherein the plastic half shells are lined with a foam plastic material which is firmly connected thereto by means of an adhesive agent.

Another object of this invention is to provide a model airplane of the type described which includes a longitudinal sectional bar disposed in the fuselage and embedded in the foam plastic material, and wherein the longitudinal sectional bar includes means for supporting a motor, a-fuel tank, a remote control unit, a nose wheel and the wings, whereby an impact load transmitted to the longitudinal sectional bar through the supporting means will be conveyed to the foam plastic material and evenly distributed therethrough thereby reducing the possibility of an impact failure at a particular point in the air plane. i

Still another object 'of this invention is to provide a model airplane of the type described wherein damage to the wings upon impact is prevented by supporting the wings inside the fuselage by means of a perpendicular screw which is attached at one end to an anchor plate in the wings and at its other end to a traverse bridging two longitudinal sectional bars, and wherein the traverse has a predetermined tensile strength which is lower than the tensile strength of the wings whereby an impact load applied to the wings will cause the traverse to break thereby protecting the wings from damage.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claimed subject matter and the several views illustrated in the accompanying drawings.

IN THE DRAWINGS FIG. 1 is a vertical sectional view taken through the fuselage of a model airplane formed in accordance with this invention, and illustrates the fuselage being formed of two plastic half shells which are lined with a foam plastic material.

FIG.' 2 is a fragmentary side elevation of a half shell for a fuselage of a low wing monoplane to be constructed in accordance with this invention.

FIG. 3 is a vertical sectional view taken through a fuselage of a model airplane formed in accordance with this invention, and illustrates upper and lower half shells lined with foam plastic material, and which is particularly adapted to be used in the construction of a midwing monoplane. FIG. 4 is a fragmentary vertical sectional view taken through a fuselage for a midwing monoplane formed in accordance with this invention, and illustrates in dotted lines the position of the wings along the horizontal midline thereof.

MG. 5 is a fragmentary vertical sectional view taken through the tail unit of a model airplane formed in accordance with this invention, and illustrates a bead formed in the fuselage which has been pierced and separated for reception of the horizontal tail unit.

lFlG. d is a fragmentary perspective view, shown partly in section, of half of a tail unit, and illustrates the elevator portion thereof being integrally formed therewith and adapted to be separated therefrom by means of a separating line or notch.

FIG. '7 is an exploded perspective view, shown partly in section, of the two halves of the rudder prior to separation from the respective halves of the fuselage, and further illustrates a pliable foil disposed therebetween which is adapted to provide a swivelable attachment for the rudder to the fuselage.

lFlGS. and 9 are plan views of two different forms of pliable hinge foils.

lFlG. ill is a fragmentary bottom plan view of the tail unit of a model airplane formed in accordance with this invention, and illustrates two guide cables extending from the fuselage to one of the elevators and the rudder.

FlG. ii is a fragmentary side elevation of an unfoamed half shell of a fuselage formed in accordance with this invention, and illustrates a longitudinal sectional bar disposed therein and extending through a bulkhead at the nose end thereof for supporting a motor.

H6. 112 is a fragmentary top plan view of a pair of longitudinal sectional bars connected with a transverse bulkhead and adapted to be disposed within a fuselage formed in accordance with this invention.

FIG. i3 is a vertical sectional view taken through a fuselage formed in accordance with this invention with parts thereof removed for clarity, and illustrates the position of the longitudinal sectional bars disposed therein.

lFlG. id is a vertical sectional view taken through a wing formed in accordance with this invention, and illustrates two half shells lined with foam plastic material and a wingspar embedded therein for supporting a landing gear.

P16. 115 is a front elevation of a wingspar adapted to be inserted into a wing formed in accordance with this invention.

lFlG. 116 is a plan view of a pierced holding plate adapted to be inserted into the wingspar for attachment to the torsion rod of the landing gear.

FM]. 117 is a fragmentary vertical sectional view taken through the fuselage of an airplane formed in accordance with this invention, and illustrates the attachment for supporting the wings therein.

FIG. 11% is a top plan view of the attachment for supporting the wings in the fuselage, and illustrates the traverse bridging the two longitudinal sectional bars which supports the screw that is embedded in the wings.

lFlG. MB is a fragmentary vertical sectional view taken through the attachment for supporting the wings within the fuselage, and further illustrates the manner in which the traverse and the two longitudinal sectional bars are embedded in the foamplastic material.

Referring now to the drawings in detail, there is illustrated in FIGS. lll a fuselage of a model airplane formed in accordance with this invention and consisting of two equally covering half shells It, 2 and l, 2 made of a deep drawn plastic, preferably a thermoplastic, having edges 3 which are drawn into the inside of the fuselage and thus presenting a relatively large impact and adhesive surface. Each half shell is coated with a lining i consisting of plastic foam, preferably polyurethane foam, which is partly encompassed or surrounded by the edges 3. The connection of the lining d with the half shells l, 2 or )1, 2, serving as an outer skin, is accomplished by means of a suitable adhesive agent.

FlGS. l and 2 show the fuselage of a plane for a low wing monoplane. For this purpose, the fuselage comprises the two half shells l, 2 separated by a vertical separating line 5. The fuselage thus consists of lateral half shells ll, 2 which are drawn in at their undersides in such a manner that they will fonn a support 6 and a cover 7 for the wings (not shown).

FIGS. 3 and 4 shown the fuselage for a midwing monoplane. In this case, the fuselage consists of upper and lower half shells 1', 2' which are divided by a horizontal separating line 5'. A wing 8 will be inserted through the fuselage along the horizontal separating line 5.

As seen most clearly in FIG. 5, a bead 9, projecting outwardly and being in the form of a slit, has been molded into the half shells 1, 2 in the area of the tail unit of the fuselage, the bottom of the bead 9 being easily pierced by the do-ityourselfer for reception of a horizontal tail unit 10 which can be inserted and glued to the fuselage.

As seen most clearly in FIG. 10, additional beads 11 are provided on the fuselage 10 which, after proper piercing, serve for guiding out cables 20, 21 which are connected to elevators l2 and a rudder 13 of the horizontal tail unit 10.

The elevators l2 and rudder 13 are, as seen in FIG. 6,

formed integrally in one piece with the corresponding half shells of the tail units l4, 15. A separating line or notch I6 is provided in the half shells of the tail units l4, 15 for separating the elevators l2 and rudder 13 from their respective half shells by the do-it-yourselfer prior to assembly of the model. A plastic soft foil or a pliable sheet metal plate l7, 17 (FIGS. 7-9) is then inserted as a hinge element between the half shells 1, 2 or the half shells of the horizontal tail unit 10, on the one hand, and the parts of the elevators 12 or rudder 13, on the other hand, and then connected by adhesive means with the pertinent part. As a result, in the assembled airplane model, the movable parts, mainly the ailerons, rudder and elevators, are connected swingingly with the wings or the tail unit through the plastic soft foils or bendable metal sheets l7, 17' serving as hinge elements.

' As seen most clearly in FIG. 10, pierceable slitlike beads (unnumbered) have also been provided in the elevators l2 and rudder 13 through which sheet metal plates 18, 19, respectively, bent at right angles are inserted and glued in place. Each of the sheet metal plates 18, 19 includes a bore (unnumbered) in its leg portion for reception of an end of the pertinent cable 20, 21 through which the elevators l2 and rudder 13 can be actuated by the operator of the model airplane.

The nose end of each half shell 1, 2 of the fuselage is closed by a transverse bulkhead 22 formed of plywood or other suitable material which at the same time serves as a support for an additional nose casing encompassing the motor (not shown).

Referring now to FIGS. ll, 12 and 13, there is illustrated a longitudinal sectional bar 23 which is disposed in the fuselage and embedded into the lining 4 of each half shell 1, 2 and glued firmly to its respective half shell I, 2. The longitudinal sectional bar 23 projects beyond the nose end of the fuselage and is connected positively with the transverse bulkhead 22. The longitudinal sectional bar 23 has a T-shaped cross section, including a horizontal flange 24 projecting into the inside of the fuselage. The flange 24 has several projections 25 which can be pierced and serve as mountings for a motor (not shown), a fuel tank (not shown), a nose wheel (not shown), a remote control (not shown) and the wings 8. Impact loads absorbed primarily by the nose wheel and the wings will be transmitted by the longitudinal sectional bar 23 to the foam plastic material where it will be distributed evenly. In order to distribute the impact load to a large surface of the fuselage, the longitudinal sectional bar 23 extends preferably to behind the ends of the wings 8. The longitudinal sectional bar 23 can be formed of metal, wood, plastic or other suitable material.

Within the area of the transverse bulkhead 22, the flange 24 has a recess 27 for the reception of the transverse bulkhead 22 which runs perpendicularly in relation to a vertically disposed flange 26 on each sectional bar 23, which bulkhead 22 on its part has a slit the width of the flange 24 and a recess the width of the flange 26, so that both parts can be inserted into one another positively and perpendicularly in relation to each other.

Referring now to FIG. 14, the wings 8 of the model airplane consist of half shells 28, 29 which cover each other equally and which are symmetrical in their cross sections, and the edges of which, similar to the edges 3 of the half shells l, 2, have been withdrawn toward the inside for the purpose of forming broad impact and adhesive surfaces. The half shells 28, 29 have been lined on their insides with a lining 20 preferably made of expanded polystyrene foam, which in longitudinally spaced points has been pulled to the inside of the wing 8 to form longerons 31, in order to give the necessary stability to the wings 8.

Similar to the elevators l2 and rudder 13 of the tail unit 10, the ailerons 32 of the wings 8 are formed in one piece with the half shells 28, 29, and they can then be separated prior to assembly of the model along a separating line (not shown) provided for that purpose. Subsequently they are connected swivelably with the wings 8 by means of an inserted foil 33.

A longeron 31' each half shell 28, 29 is located approximately in the middle of the wing 8 and has a longitudinal slit 34 for the reception of a wingspar 35. The wingspar 35 can be inserted laterally into the wings 8 and penetrates crosswise through the fuselage. The wingspar 35 extends on each side of the fuselage to a point approximately above the wheels 36 of the landing gear. The wingspar 35 is formed of relatively thick plywood or similar material and includes cut out portions 37 for decreasing its weight. The wingspar 35 further includes a generally perpendicular bore 38 formed on each side thereof close to the sides of the fuselage to receive one end 39 of a cropped torsion rod 40 of the landing gear, whose middle part 41 fits against the underside of the wingspar 35.-The wingspar 35 further includes several cross slits 42 on its underside for the reception of small pierced holding plates 43,- illustrated in FIG. 16, which are adapted to support the middle part 41 of the torsion rod 40.

Referring now to FIGS. I7 19, a traverse 44, formed for example of a wooden board, rests inside the fuselage on the projections 25 of the longitudinal sectional bars 23. The traverse 44 includes a middle bore through which a screw 45 is disposed vertically downwardly. The screw 45 is attached to an anchoring plate 46 located in the rear part of the ends of the wings 8 arranged in the fuselage. The traverse M has a known predetermined tensile strength which is less than the tensile strength of the wings 8. In the case of a crash of the model airplane, the impact load absorbed by the wings 8 will be transmitted to the transverse 44 which will then break thereby preventing damage to the wings 8. The traverse 44 can then be replaced easily and economically whereas the wings 8 could only be replaced or repaired at considerable expense.

From the foregoing it should be readily apparent that there is provided in accordance with this invention a model airplane that is both economical and that withstands impact loads without damage to the vital parts of the airplane. Variations in the wing profiles, in the degree of foaming of the half shells and the shaping of the individual components of the airplane are possible within the framework and scope of this invention.

For example, it is possible to line the tail unit only partially with a plastic foam in order to keep it more elastic or in order to save weight. Furthermore, half shells prelined with plastic foam can be deep drawn from foils or can be compressed from a plastic granulate with the lining subsequently inserted. It is also possible to form a foam body of the desired configuration and to cover it subsequently with a plastic foil.

Although only preferred embodiments of the invention have been specifically illustrated and described herein, it is to be understood that minor variations may be made without departing from the spirit of the invention.

We claim:

1. A model airplane comprising a fuselage, wings and a horizontal ltailunit; said fuselage, said wings and said horizontal tail unit being formed of plastic half shells, said plastic half shells being lined with a foam plastic material, a longitudinal sectional bar disposed in said fuselage and embedded in said foam plastic material, said longitudinal sectional bar includes means for supporting a motor, a fuel tank, a remote control unit, a nose wheel and the wings, whereby an impact load transmitted to said sectional bar through said supporting means will be conveyed to said foam plastic material and evenly distributed therethrough thereby reducing the possibility of an impact failure at a particular point in the airplane.

2. A model airplane comprising a fuselage, wings and a horizontal tail unit; said fuselage, said wings and said horizontal tail unit being formed of plastic half shells, said plastic half shells being lined with a foam plastic material, a longitudinal sectional bar disposed in sad fuselage and embedded in said foam plastic material, said fuselage includes a nose end and a tail end, a transverse bulkhead disposed in said nose end and embedded in said foam plastic material, and said longitudinal sectional bar is positively connected with said bulkhead and extends therethrough beyond said nose end for supporting a motor.

3. A model airplane comprising a fuselage, wings and a horizontal tail unit; said fuselage, said wings and said horizontal tail unit being formed of plastic half shells, said plastic half shells being lined with a foam plastic material, said wings include ailerons and said tail unit includes elevators and a rudder; sad ailerons, elevators and rudder being integral with the respective half shells of the wings and tail unit, and notch means in the respective half shells for separating the ailerons, elevators and rudder from the wings and tail unit respectively.

4. A model airplane as defined in claim 3 wherein said separated ailerons, elevators and rudder are hinged to their respective half shells by means of pliable foil sheets.

5 A model airplane comprising a fuselage, wings and a horizontal tail unit; said fuselage, said wings and said horizontal tail unit being formed of plastic half shells, said plastic half shells being lined with a foam plastic material, said fuselage includes a pierceable slitlike bead for reception of said horizontal tail unit, said additional pierceable slitlike bead means for guiding out cables that can be connected with elevator and rudder means.

6. A model airplane comprising a fuselage, wings and a horizontal tail unit; said fuselage, said wings and said horizontal tail unit being formed of plastic half shells, said plastic half shells being lined with a foam plastic material, a longitudinal sectional bar disposed in said fuselage and embedded in said foam plastic material, the wings are supported inside the fuselage by means of a perpendicular screw which is attached at one end to an anchor plate in the wings and at its other end to a traverse carried by the longitudinal sectional bar, and wherein the traverse has a predetermined tensile strength which is lower than the tensile strength of the wings whereby an impact load carried to the wings will cause the traverse to break thereby protecting the wings from damage. 

1. A model airplane comprising a fuselage, wings and a horizontal tail unit; said fuselage, said wings and said horizontal tail unit being formed of plastic half shells, said plastic half shells being lined with a foam plastic material, a longitudinal sectional bar disposed in said fuselage and embedded in said foam plastic material, said longitudinal sectional bar includes means for supporting a motor, a fuel tank, a remote control unit, a nose wheel and the wings, whereby an impact load transmitted to said sectional bar through said supporting means will be conveyed to said foam plastic material and evenly distributed therethrough thereby reducing the possibility of an impact failure at a particular point in the airplane.
 2. A model airplane comprising a fuselage, wings and a horizontal tail unit; said fuselage, said wings and said horizontal tail unit being formed of plastic half shells, said plastic half shells being lined with a foam plastic material, a longitudinal sectional bar disposed in sad fuselage and embedded in said foam plastic material, said fuselage includes a nose end and a tail end, a transverse bulkhead disposed in said nose end and embedded in said foam plastic material, and said longitudinal sectional bar is positively connected with said bulkhead and extends therethrough beyond said nose end for supporting a motor.
 3. A model airplane comprising a fuselage, wings and a horizontal tail unit; said fuselage, said wings and said horizontal tail unit being formed of plastic half shells, said plastic half shells being lined with a foam plastic material, said wings include ailerons and said tail unit includes elevators and a rudder; sad ailerons, elevators and rudder being integral with the respective half shells of the wings and tail unit, and notch means in the respective half shells for separating the ailerons, elevators and rudder from the wings and tail unit respectively.
 4. A model airplane as defined in claim 3 wherein said separated ailerons, elevators and rudder are hinged to their respective half shells by means of pliable foil sheets. 5 A model airplane comprising a fuselage, wings and a horizontal tail unit; said fuselage, said wings and said horizontal tail unit beinG formed of plastic half shells, said plastic half shells being lined with a foam plastic material, said fuselage includes a pierceable slitlike bead for reception of said horizontal tail unit, said additional pierceable slitlike bead means for guiding out cables that can be connected with elevator and rudder means.
 6. A model airplane comprising a fuselage, wings and a horizontal tail unit; said fuselage, said wings and said horizontal tail unit being formed of plastic half shells, said plastic half shells being lined with a foam plastic material, a longitudinal sectional bar disposed in said fuselage and embedded in said foam plastic material, the wings are supported inside the fuselage by means of a perpendicular screw which is attached at one end to an anchor plate in the wings and at its other end to a traverse carried by the longitudinal sectional bar, and wherein the traverse has a predetermined tensile strength which is lower than the tensile strength of the wings whereby an impact load carried to the wings will cause the traverse to break thereby protecting the wings from damage. 